Safety electric switch



May 3, 1932.

L.E.KOCH

SAFETY ELECTRIC SWITCH Filed Jan. 28.

1927 2 Sheets-Shet -1 y 1932. L. E. KOCH 1,856,077

v SAFETY ELECTRIC SWITCH Filed Jan. 28, 1927 2 Sheets-Sheet 2 tain a liquid at a predetermined level in a Patented May 3, 1932 'UNITED STATES PATENT OFFICE EAWRENGE E. KOCH, OF ELK HABT, INDIANA, ASSIGNOR, BY MESNE ASSIGNMENTS, TO MINNEAPOLIS-HONEYWELL REGULATOR COMPANY, OF MINNEAPOLIS, MINNESOTA,

CORPORATION OF DELAWARE SAFETY ELECTRIC SWITCH Application filed January 28, 1927. Serial No. 164,186.

' This invention relates to electrical switches and has special reference to a safety switch actuated and controlled bya float. n

More particularly, this invention relates to tiltable switches of the mercury contactor type, which are used for the control of a liquid supply and are actuated and controlled by a float.

Although this invention may be employed in anyinstance where it is desired to maintank, it is particularly adapted to be used as a safety switch whereby, in the event that a defect such as a faulty connection or the like should exist in the liquid supply line or a leak occur in the apparatus associated with the-tank, the present invention acts to shut down the supply of liquid to the tank.

Hereinafter this invention will be described inconnection with an automatic heating system employing a liquid fuel, the safety switch being mounted on and adapted to control the amount of liquid in an auxiliary tank supplied from a suitable'source of supply and at a point remote from said auxiliary tank.

. lit is-usual in all types of automatic heating systems to control the devices which permit fuel to flow and to urge combustion by pro-' viding Various sw1tch1ng means in an electrical' circuit and having them operate in a proper sequence. Should the burner fail to ignite for lack of oil or should the motor fail to operate or the system be out of order in some other manner and from other like causes, it is usual to provide a safety switch to disconnect the fuel supply and the ignition means from the system and-thus terminate the operation of the heating system. 7

However, the apparatus in theforegoing system may be perfect and approved by experts who are orga'ni zed to give such opinion,

but the installation of the heating system cannot always be so approved. Defects in the connecting of the pipes conducting the liquid fuel to the burner may cause serious fire "hazards, which may not be controlled by the safety switch of the apparatus and the present invention is designed to eliminate this hazard. The safety switch of the installation is disposed on or adjacent the auxiliary tank and is operated by a float, which, when it rises to a predetermined level, opens the I switch and when it falls to a predetermined level, closes the switch. When the liquid in the auxiliary tank falls still further despite the operation of the pump supplying the tank, the switch actuates to open the clrcuit through the motor thus discontinuing the further supply of liquid to the tank.

@ne of the objects of this invention is to provide a safety control for an auxiliary supply tank. 'A further object of this invention is to provide an electrical switch, which, when the liquid supply in an auxiliary tank de- *on the line 2-2 of F igl 1 and showing the casing in section;

- Fig. 3 is a vertical sectional view taken on the line 33 of Fig. 1;

Fig. 4 is a detail sectional view taken on the line 44 of Fig. l;

Fig. 5 is a more or less diagrammatic view of an installation showing the electrical switch disposed therein;

Fig. 6 is a diagrammatic View of the switch showing an open position thereof;

Fig. 7 is a view similar to Fig. 5 showing the switch in a closed position; and

Fig. 8 is a View similar to Fig. 5 showing a third position of the switch in an open position.

Referring now to the drawings and more particularly to Fig. 5 thereof, a furnace 10 of any usual type is shown having a combustion due 11 extending into thedash pot of is ignited in the usual manner and as is well known in practice. The auxiliary tank 12 is supplied with a liquid fuel from a main supply 13 by a motor driven pump 14 through pipe 15, the pipe 16 being merely the overflow from the pump 14. A switch 17, being the safety control switch, is'mounted on the auxiliary tank 12 in any suitable manner and operates to control the li uid level within said tank as shall hereina ter be explained.

The safety control switch 17 comprises a casing 18 which is enclosed by a cover 19. A tiltable mercury tube contactor switch 20 is mounted within said casing 18 and in a clip 21 which clip is in turn fixedly mounted to a collar 22. An arm 23 is also fixedly mounted on said collar 22 and extends to a position between stop members 24 and 25. A second. arm 26 is pivotally mounted on said collar 22, said pivotal connection being obtained by means of a bracket 27 preferably integral with said arm. A bolt 28 extends through collar 22 and secures said collar to the rear wall of the casing 18, a washer 29 actin as a spacer between said wall and said collar 22.

The contactor 20 comprises a sealed container having a pair of spaced cooperating electrodes positioned adjacent one end thereof and a body of current conducting fluid such as mercury, which is adapted to bridge the electrodes in one position thereof to complete an electrical circuit therethrough. The electrodes are connected to suitable contact plates by wires 20 and thence to the motor of the pump 14 b wires 20, said contact plates being mounte on a termlnal block 20. The

terminal block is suitably mounted within 2. slpring member 30 which as the liquid level a s or rises will tend to move the switch in one of two directions with ra idity after said contactor is past such a position in which the arms 23 and 26-are horizontal. The spring 30 is fastened at one end to a lug 31 on the arm 23 and is. fastened on the other end to an arcuate member 32 (it being necessary in this instance to employ an arcuate member in order to extend around the collar 22), which I is in turn pivotally mounted at 33 to the arm 26. This construction, which has just been described, will hereinafter be referred to as a spring biased linkage construction.

The arm 26 is bifurcated at its outer end to slidably enga e a pin 34 projecting from a rod 35 which re extends through the casing 18. At the upper end of the rod 35 is secured a handle 36 for conveniently manually operating the rod. The lower end of the rod is secured to a float 37 which is disposed in the auxiliary tank 12. In the operation of the switch, the float 37 rises as liquid is supplied to the auxiliar tank and moves the arm 26 upwardly. T e upward movement of the arm 26 has no effect on the collar 22, being pivotally mounted thereon, and therefore, the contactor 20 remains stationary until at such a time as the rod 26 passes a plane in which both the arms 23 and 26 are horizontal, whereafter the spring 30 moves the'arm 23 u wardly untilsaid arm strikes the stop mem er 24. The arm 23, being fixedly secured to the collar 22, tilts the contactor to a position such as is clearly illustrated in Fig. 6 of the drawings and shows the mercury to the right of the contactor in an open circuit osition. This, of course, opens the circuitt rou h the motor and shuts off the supply of liquid to the auxiliary tank. As the supply in said auxiliary tank de creases upon its use in the furnace 10, the float 37 falls and moves the rod 35 downwardly. The arm .26 moves downwardly with the rod 35 and, as before stated, it being loosely mounted on the collar 22 has no effect upon said collar until at such a time as the arm 26 passes a position in which the arms 23 and 26 are in a horizontal plane, whereafter thespring 3O urges the arm 23 downwardly until it engages the stop member 25. The arm 23, bein fixed to the collar 22, causes a rotation of t e collar 22 which tilts the contactor 20 into a closed circuit osition as shown clearly in Fig. 7 of the rawings. The motor a ain operates the pump to supply the auxi iary tank with a liquid to a predetermined level and the cycle I of operation is repeated.

The aforementioned operation is the normal operation of the liquid in the auxiliary tank. However, due to defects in the supply line or apparatus, should the liquid in the tank decrease at such a rate that is abnormal and not in keeping with the supply ordinarily consumed by the furnace 10, the float 37 would continue its downward movementfrom the position as shown in Fig. 7. In this instance, the rod 35 would continue to move the arm 26 downwardly and a lug 38 on the arm 26 would engage a projection 39 on the arm 23, which is fixed on the collar 22, and cause the collar 22 to rotate and tilt the contactor 20 into an open circuit position such as shown in Fig. 8 of the drawings.

It is thus apparent that there are three distinct positions of the arm 26 and the rod 353 the upper position as shown in Fig. 6 being an o n circuit osition indicative of a full supp y of oil in the auxiliary tank; the second position as shown in Fig. 7 of the drawings being a closed circuit position in which the lowest level of the liquid in the shut off the supply of liquid to the auxiliary tank and is indicative of the fact that an abnormal supply of liquid is being drawn from the auxiliary tank.

'It may be advisable, in case the supply of liquid to the auxiliary tank is shut off, to make this fact known to the attendant. As a means for accomplishing this end, one of the supports 40 for the terminal block 20 may be of a suitable conducting material and insulated from the casing whereby an electrical circuit is completed through a bell or some such alarm by means of the arm 26 bearing against said support 40 in its lowered position. To complete this circuit, a wire 41 is connected to the support and extends to one side of the bell, the other side of the bell and the casing being suitably grounded.

After an open circuit position has been obtained in the safety control switch 17, it is desirable that the same shall not return to an operative position except that it may be manually restored. This is accomplished by manually lifting the handle 36 on the rod 35 upwardly to actuate the contactor 20 as has been heretofore described with reference to the normal control of the fuel supply in the auxiliary tank. However, it would require a great length of time for the oil to reach such a level as to normally operate the switch and it would be impractical to manually hold the handle in such a position until this condition occurred. Therefore, a locking means has been provided comprising a gravity weighted lever 42 pivoted on the upper'side of the casing 18 and extending downwardly therein. The upper end of this lever is provided with a handle 43, which extends outside of the casing and is readily accessible for manual manipulation. The lower end of the lever is provided with a hook 44:, which, when pivoted to a position beneath the arm 26, holds the same in such a position until the liquid rises to elevate the float 37 and raises the arm 26 out of engagement with the.

hook, whereafter said lever will move back to its original vertical position and out of the plane in which the arm 26 is positioned. It will be noted that the normal operation of the arm 26 will not in any way be hindered by the lever 42 until at such time as the lever is man ually moved into engagement with the arm. When a normal operation of the switch is resumed, the lever is again out of the way of the further operation of the switch.

As illustrative of the further usefulness of this safety control switch,-it may be recited ply of liquid fuel is not to be obtained from the auxiliary tank. Such a system and apparatus has been, fully described in a pending application filed November 30, 1926, and

95 given Serial No. 151,704. In this application,

it does not seem to be necessary'to go into the details of a structure such as will operate to perform the aforesaid function. I

By applying the present invention to a system as just recited, the latter is controlled by the former as the heating system is dependent upon a supply of liquid fuel for its successful operation. For example, should a faulty connection exist in the supply line or should a leak occur in the apparatus supplying the liquid to the heating system or should any like defect in the installation become present, a

supply of fuel may not be obtained by the heating system and the operation thereof is terminated.

As a result of this invention, in the event of a defect in the installation of any apparascope of the appended claimsand the prior art.

I claim 4 1. In a. device of the character described, switching means, operating mechanism therefor, a float actuated by a quantity of liquid in a container and for actuating said operating mechanism, said operating mechanism having two normally operative positions for efi'ecting an open and a closed circuit through said switching means and a third operative position for efi'ecting anopen circuit therethrough upon obtaining an abnormal fluctuation of the quantity of liquid in said container, means for manually restoring said switching means to one of said normally operative positions, and means for holding said switching means in one of said normalfor, a float actuated by a quantity of liquid in a container and for actuating said operating mechanism, said operating mechanism having two normally operative positions for effecting an open and a closed circuit through said switching means and a third operative position for effecting an open circuit therethrough upon obtaining an abnormal fluctuation of the quantity of liquid in said container, means for manually restoring said switching means to one of said normally operative positions, and a gravity weighted member for holding said switching means in one of said normally operative positions until switching means, operating mechanism therer said abnormal fluctuation is overcome whereafter said member is automatically released.

3. In a device of the character described, switching means, operating mechanism therefor, a float actuated by a quantity of liquid in a container and for actuating said operating mechanism, said operating mechanism having two normally operative positions for effecting an open and a closed circuit through said switching means and a third operative position for effecting an open circuit therethrough upon obtaining an abnormal fluctuation of the quantity of liquid in said container, means for manually restoring said switching means to one ofsaid normally operative positions, and a gravity weighted member manually operated into a position to hold said switching means in one of said normally operative positions until said abs normal fluctuation is overcome whereafter' said member is automatically released.

In witness whereof I have hereunto subscribed my name.

LAWRENCE E. KOCH. 

